Colorectal cAncer and CrohN's DIsease study (CANDID): An international multicentre retrospective audit

Background: Inflammatory bowel disease (IBD) affects more than 10 million people worldwide. Men and women are equally affected by Crohn's disease (CD). It has been shown that patients with CD are at an increased risk of a colorectal cancer (CRC) diagnosis and CRC-related mortality. During the last two decades, biological therapies have revolutionized the treatment of CD. There are no current studies investigating the prevalence of CRC in patients with CD in the era of biological therapy and the possible features of patients with CD who are at high risk of developing CRC. Aim: We aim to assess the prevalence of CRC, risk factors and profile of CRC in patients with CD receiving biological treatment compared with those who are not under biological therapy and the impact of CD-associated colorectal strictures on CRC development. The study hypothesis is that the use of biological therapy in the control of CD activity may decrease the risk of developing CRC. Study design and setting: An international, retrospective, snapshot of the prevalence of CRC in patients with CD, reported according to the SPIRIT guidelines. The study will involve centres that hold regular IBD multidisciplinary team meetings and have both IBD colorectal surgeons and gastroenterologists. Each participating centre will provide a local consultant lead and a local trainee lead. Data will be collected within a 2-year recruitment period (January 2017-January 2019). Study population: Adult patients who presented with CD during the study period. Patients with an incidental diagnosis of CD during evaluation for CRC will be excluded. Statistical plan: Baseline patient characteristics will be summarized using the appropriate descriptive statistics. Univariable, multivariable and Cox regression models will be used to identify factors significantly associated with CRC. For noncontinuous variables a comparison between the subgroups will be carried out using the chi-square test corrected by Fisher's exact test if appropriate. A p-value of <0.05 will be considered statistically significant. Data storage: Data will be stored on a secured server, pin-code protected according to the local data management agreement.